A harmonic model for the temporal variation of lightning activity over Africa

• Published in: Journal of Geophysical Research 2011-03, Vol.116 (D5), p.1D-n/a, Article D05105
• Main Authors: Collier, A. B., Hughes, A. R. W.
• Format: Article
• Language: English
• Subjects: Annual variations; Geophysics; lightning; Tropical environments
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2010JD014455

Concise rainfall, temperature, and humidity climatologies are available for most countries, reflecting the regular annual variation of these quantities, usually with monthly resolution. Although numerous surveys of global and regional lightning activity exist, no comparable national climatologies of lightning activity are available. Annual lightning flash rate patterns for most African countries are derived here using 10 years of data from two satellite lightning detectors. These patterns can be represented accurately by annual and semiannual sinusoidal components superimposed on a mean level. The highest‐average lightning activity (47.8 km−2 yr−1) occurs in the Democratic Republic of the Congo, while the lowest (0.2 km−2 yr−1) is found in Egypt. Very little lightning is observed in the Sahara, while a consistently high intensity is found throughout the tropics. There is a clear reversal in the phase of the annual component across the equator. Within the tropics the amplitude of the semiannual variation is a significant fraction of that of the annual variation but becomes less important in the subtropics.